Many implantable medical devices such as pacemakers, defibrillators and neural stimulators can sense various physiological parameters through medical leads and/or deliver therapy to tissue. Leads include an elongated flexible lead body. The lead body comprises one or more insulated elongated conductors with one or more electrodes disposed at a distal end of the conductors.
To ensure the lead is properly secured to an implantable medical device, the proximal end of the conductor, referred to as a terminal pin, is passed through a conductor bore in the connector block of a header. A setscrew, which passes through a threaded setscrew bore that intersects with the lead bore, is positioned to contact the conductor. A very small surgical torque wrench is then used to apply a certain amount of torque to the setscrew. Torque applied to the setscrew should provide a retention force between the setscrew and the conductor that is sufficiently large to prevent the conductor from dislodging from the header yet low enough to prevent the torque from damaging the setscrew or conductor. After the setscrew has been tightened, the torque wrench is typically discarded to ensure contaminants from one surgical procedure are not transferred to another procedure. It is desirable to develop surgical torque wrenches that apply appropriate torque to a setscrew when securing a lead to a header and that are also inexpensive in order to reduce the cost of such procedures to patients.